This invention relates to a character reading camera which produces electrical signals representive of optical characters in an object plane scanned by the camera.
Character reading cameras are commonly used in character recognition systems where optical characters are scanned by a camera and the resulting electrical signals are processed to identify and record the characters and/or to display the scanned characters on a screen. Typical uses for such a character recognition system are in automatic signature readers and label reading in a computerised merchandising inventory control. Such cameras typically comprise a linear array of photo-sensors, an optical system which focuses a vertical slice of the character being read onto the photosensors and a wheel or roller driven pulse generator which engages with the surface on which the character is printed to produce pulses for each given scan distance increment. The electrical information from the photo-sensor array is stored for each scan increment and the total information obtained from the scanning of a character is compared with a series of prestored signals representing ideal characters.
A different type of application for a character reading camera, and one of particular interest in the present specification, is as a component in a reading aid for the partially sighted. Hitherto reading aids have essentially comprised a closed circuit television system where a page to be read is traversed by a television camera and a display screen reproduces in magnified form the characters scanned by the camera. Such systems are bulky and leave unsatisfied a vast need for a portable reading aid. An aid meeting this requirement can be produced using a character reading camera in conjunction with a digital store and a visual display unit. A reading aid of this type has been described in Browne, "A Reading Aid for the Partially sighted", Electronics & Power, August 1978, 592.